Photon up-conversion film, manufacturing method for photon up-conversion film, photon up-conversion body, laminate, and energy conversion device

Abstract

Provided are a photon up-conversion film, a photon up-conversion body, a laminate, and an energy conversion device with which high-efficiency up-conversion can be achieved, and manufacturing methods thereof. A photon up-conversion film according to an embodiment of the present invention is provided with a color development portion including at least a sensitization component capable of absorbing light in a first wavelength region λ1 and a light emission component capable of emitting light in a second wavelength region λ2 that has wavelengths shorter than in the first wavelength region λ1. In the photon-up conversion film, a relaxation time measured by a spin-echo method using a time domain nuclear magnetic resonance method (pulse NMR) at 298 K is less than 210 ms.

Description

Photon upconversion film, method for manufacturing photon upconversion film, photon upconversion body, laminate, and energy conversion device

[0001] The present invention relates to a photon upconversion film, a method for manufacturing a photon upconversion film, a photon upconversion body, a laminate, and an energy conversion device.

[0002] Photon upconversion (hereinafter sometimes simply referred to as "upconversion") technology, which converts low-energy light into high-energy light, is expected to be applied to various fields such as solar cells or photovoltaic power generation, photocatalysis, bioimaging, and optical devices. A known upconversion luminescence technique in organic materials utilizes triplet-triplet annihilation (TTA), which occurs when triplet-state molecules collide with each other. Among the upconversion techniques that utilize TTA (TTA-UC), in solution systems in which donor compounds and acceptor compounds are dissolved in a solvent, energy is efficiently transferred by diffusion between the donor compound molecules and the acceptor compound molecules. However, the solution system presents a problem in that the fields in which it can be put to practical use are limited.

[0003] Due to the above circumstances, research and development into upconversion luminescence in the solid state has been progressing. However, since molecular diffusion hardly occurs in the solid state, there is a problem that TTA cannot be used efficiently. For example, resin films incorporating donor compounds and acceptor compounds have been investigated, but the upconversion luminescence efficiency is insufficient.

[0004] Patent No. 5491408

[0005] The present invention has been made to solve the above-mentioned problems of the prior art, and its main object is to provide a photon upconversion film, photon upconversion body, laminate, and energy conversion device capable of highly efficient upconversion, as well as methods for manufacturing each of them. Also, it is an object of the present invention to provide a photon upconversion film, photon upconversion body, laminate, and energy conversion device capable of high transmittance and highly efficient upconversion by optimizing the medium, as well as methods for manufacturing each of them.

[0006] [1] A photon upconversion film according to one embodiment of the present invention includes a color-forming portion. The color-forming portion includes at least a sensitizing component and a light-emitting component. The sensitizing component is capable of absorbing light in a first wavelength region λ1. The light-emitting component is capable of emitting light in a second wavelength region λ2, the wavelength of which is shorter than the first wavelength region λ1. The photon upconversion film has a relaxation time of less than 210 ms measured by a spin-echo method using time-domain nuclear magnetic resonance (pulse NMR) at 298 K. [2] The photon upconversion film according to [1] above may further include a matrix. The color-forming portion is dispersed in the matrix as a dispersed phase. [3] In the photon upconversion film according to [2] above, the matrix may be composed of a resin. [4] In the photon upconversion film according to [3] above, the resin may include polyethylene oxide and / or a polyvinyl alcohol-based resin. [5] In the photon up-conversion film according to any one of [1] to [4] above, the color-forming portion may contain a solvent having a boiling point of 80°C or higher. [6] In the photon up-conversion film according to any one of [1] to [5] above, the color-forming portion may contain a solvent having a viscosity of 0.6 mPa·s or higher at 23°C. [7] In the photon up-conversion film according to any one of [1] to [6] above, the color-forming portion may contain a monomolecular liquid crystal compound. [8] In the photon up-conversion film according to any one of [3] to [7] above, the sensitizing component may be used in an amount of 7.00×10 per 1 g of the resin. －９ mol~5.00×10 －６ mol and the above luminescent component is 5.00 × 10 －６ mol~7.00×10 －５mol. [9] A method for producing a photon upconversion film according to another aspect of the present invention is the method for producing a photon upconversion film according to any one of [1] to [8] above, and includes the steps of preparing an emulsion from a medium in which the sensitizing component and the luminescent component are dispersed and / or dissolved, and an aqueous solution containing a water-soluble resin; applying the emulsion to a substrate to form a coating film; and drying the coating film.

[10] A laminate according to another aspect of the present invention includes the photon upconversion film according to any one of [1] to [8] above.

[11] An energy conversion device according to yet another aspect of the present invention includes the photon upconversion film according to any one of [1] to [8] above.

[12] A photon upconversion body according to yet another aspect of the present invention includes a color-developing portion. The color-developing portion includes at least a sensitizing component and a luminescent component. The sensitizing component is capable of absorbing light in the first wavelength region λ1. The light-emitting component is capable of emitting light in a second wavelength region λ2 that is shorter than the first wavelength region λ1. The photon upconversion film has a relaxation time of less than 210 ms as measured by spin-echo spectroscopy using time-domain nuclear magnetic resonance (pulse NMR) at 298 K.

[0007] According to the embodiments of the present invention, it is possible to realize a photon upconversion film, a photon upconversion body, a laminate, an energy conversion device, and their respective manufacturing methods, which are capable of highly efficient upconversion. Furthermore, it is possible to realize a photon upconversion film, a photon upconversion body, a laminate, an energy conversion device, and their respective manufacturing methods, which are capable of highly transparent and highly efficient upconversion by optimizing the medium.

[0008] FIG. 1 is a conceptual diagram of energy levels illustrating the mechanism of upconversion.

[0009] Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

[0010] A. Mechanism of Photon Up-Conversion The mechanism of photon up-conversion will be explained with reference to Figure 1. First, the sensitizing component (donor) absorbs incident light and converts it to an excited singlet state S Ｄ Intersystem crossing from Ｄ Then, triplet-triplet energy transfer (TTET) occurs from the donor to the emissive moiety (acceptor), resulting in the excited triplet state T Ａ is generated. Then, the triple excited state T Ａ When acceptors in the 10-12 ion-exchange state approach each other within a range where diffusion, collision, or energy transfer is possible, triplet-triplet annihilation (TTA) occurs. As a result, the acceptor reaches the higher excited singlet energy state S Ａ is generated. This high excited singlet energy state S Ａ Upconversion light (light with more energy than the pump light) is emitted from the

[0011] B. Overall Configuration of the Photon Upconversion Film A photon upconversion film (hereinafter sometimes referred to as an upconversion film) according to an embodiment of the present invention includes a color-forming portion. The color-forming portion includes at least a sensitizing component (donor) and a light-emitting component (acceptor). The sensitizing component is capable of absorbing light in a first wavelength region λ1. The light-emitting component is capable of emitting light in a second wavelength region λ2, which has a wavelength shorter than that of the first wavelength region λ1. Typically, the sensitizing component and the light-emitting component are located in close proximity to each other to enable energy transfer. In such a photon upconversion film, if the relaxation time measured by the spin-echo method using time-domain nuclear magnetic resonance (TD-NMR, pulsed NMR) at 298 K (24.85°C) is less than 210 ms (milliseconds), the absolute quantum yield of the upconversion film can be improved. This allows for the realization of an upconversion film capable of highly efficient upconversion. Furthermore, by optimizing the medium, it is possible to improve the transmittance and create a highly efficient upconversion film.

[0012] In one embodiment, the photon up-conversion film further includes a matrix, and the color-forming moiety is dispersed in the matrix as a dispersed phase. The photon up-conversion film typically has an islands-in-a-sea structure.

[0013] The domain size of the color-forming portion is, for example, 0.05 μm to 10 μm, preferably 0.1 μm to 10 μm, more preferably 0.1 μm to 5.0 μm, and even more preferably 1.0 μm to 5.0 μm. The domain size of the color-forming portion is measured, for example, by observing the cross section with a scanning electron microscope (SEM) or the surface with an optical microscope. If the domain size of the color-forming portion is within this range, the luminous efficiency of the upconversion film can be stably improved.

[0014] The content of the color-forming portion in the upconversion film is, for example, 1.0 to 60% by volume, and preferably 5.0 to 50% by volume. The content of the color-forming portion is measured, for example, by any appropriate image processing of a cross-sectional SEM image. If the content of the color-forming portion is within this range, the luminous efficiency of the upconversion film can be more stably improved.

[0015] The thickness of the upconversion film is, for example, 5 μm to 200 μm, preferably 10 μm to 150 μm, and more preferably 15 μm to 100 μm. When the thickness of the upconversion film is in this range, the color-forming portion can be well dispersed throughout the entire thickness of the film, and the desired upconversion can be stably achieved.

[0016] C. Details of the Photon Upconversion Film As described above, in the photon upconversion film, the relaxation time (average relaxation time) measured by TD-NMR at 298 K (24.85°C) is less than 210 ms, preferably 150 ms or less, more preferably 90 ms or less, and even more preferably 80 ms or less. The relaxation time (average relaxation time) can be measured, for example, by the spin-echo method. The lower limit of the relaxation time (average relaxation time) measured by TD-NMR at 298 K is typically 20 μs, and typically 6 μs. Details of the method for measuring the relaxation time (average relaxation time) will be described in the Examples section below. If the relaxation time measured by TD-NMR at 298 K is within this range, it is inferred that the color-forming moieties contained in the upconversion film are present in a form that allows efficient energy transfer at 298 K. It is also inferred that a highly efficient upconversion phosphor can be obtained by reducing energy loss due to non-radiative deactivation in the color-forming moieties. Therefore, in the color-forming portion, the sensitizing component and the light-emitting component can be molecularly diffused, and energy can be efficiently transferred.

[0017] In one embodiment, the color-developing portion contains a medium capable of dissolving and / or dispersing the sensitizing component and the light-emitting component, thereby facilitating molecular diffusion between the sensitizing component and the light-emitting component in the color-developing portion, thereby further improving the luminous efficiency of the upconversion film.

[0018] D. Medium for Color Forming Moiety Examples of the medium include a monomolecular liquid crystal compound and / or a solvent. The medium may be used alone or in combination.

[0019] When the color-forming portion contains a monomolecular liquid crystal compound, the absolute quantum yield of the upconversion film can be further improved. The monomolecular liquid crystal compound may exhibit liquid crystallinity or crystallinity at 298 K (24.85°C). The monomolecular liquid crystal compound may be a nematic liquid crystal compound, a smectic liquid crystal compound, or a cholesteric liquid crystal compound. The monomolecular liquid crystal compound is preferably a nematic liquid crystal compound.

[0020] Monomolecular liquid crystal compounds that exhibit liquid crystallinity at 298 K (hereinafter, sometimes referred to as room-temperature liquid crystal compounds) are typically capable of dissolving sensitizing components and light-emitting components. Examples of room-temperature liquid crystal compounds include cyanobiphenyls, cyanophenylcyclohexane esters, alkoxyphenyl tolanes, and Schiff bases. Room-temperature liquid crystal compounds can be used alone or in combination. Among the room-temperature liquid crystal compounds, preferred are cyanobiphenyls, cyanophenylcyclohexane esters, and alkoxyphenyl tolanes.

[0021] Examples of cyanobiphenyls include 4-cyano-4'-alkylbiphenyls such as 4-cyano-4'-pentylbiphenyl, 4-cyano-4'-hexylbiphenyl, 4-cyano-4'-heptylbiphenyl, and 4-cyano-4'-n-octylbiphenyl.

[0022] Examples of cyanophenylcyclohexane esters include 4-cyano-4'-alkylphenylcyclohexane esters such as 4-cyano-4'-pentylphenylcyclohexane ester, 4-cyano-4'-butylphenylcyclohexane ester, and 4-cyano-4'-propylphenylcyclohexane ester.

[0023] Examples of the alkoxyphenyl tolanes include 4-alkoxy-4'-alkylphenyl tolanes such as 4-ethoxy-4'-butylphenyl tolane, 4-methoxy-4'-ethylphenyl tolane, and 4-butoxy-4'-propylphenyl tolane.

[0024] A monomolecular liquid crystal compound that exhibits crystallinity at 298 K (hereinafter, sometimes referred to as a high-temperature liquid crystal compound) may be capable of forming a solid solution of the sensitizing component and the light-emitting component at 298 K (24.85°C), or may be capable of dispersing the sensitizing component and the light-emitting component.

[0025] Examples of high-temperature liquid crystal compounds include cyanophenylcyclohexanes, cyanophenyl esters, alkoxyphenyl esters, alkoxyphenylcyclohexane esters, and alkoxycyanobiphenyls. The high-temperature liquid crystal compounds can be used alone or in combination. Among the high-temperature liquid crystal compounds, preferred are cyanophenylcyclohexanes, cyanophenyl esters, alkoxyphenyl esters, alkoxyphenylcyclohexane esters, and alkoxycyanobiphenyls.

[0026] Examples of cyanophenylcyclohexanes include 4-cyano-4'-alkylphenylcyclohexanes such as 4-cyano-4'-pentylphenylcyclohexane and 4-cyano-4'-propylphenylcyclohexane.

[0027] Examples of cyanophenyl esters include 4-cyano-4'-alkylphenyl esters such as 4-cyano-4'-nonylphenyl ester, 4-cyano-4'-ethylphenyl ester, and 4-cyano-4'-butylphenyl ester.

[0028] Examples of the alkoxyphenyl esters include 4-alkyl-4'-alkoxyphenyl esters such as 4-pentyl-4'-hexyloxyphenyl ester, 4-pentyl-4'-methoxyphenyl ester, and 4-ethyl-4'-hexyloxyphenyl ester.

[0029] Examples of the alkoxyphenylcyclohexane esters include 4-alkoxy-4'-alkylphenylcyclohexane esters such as 4-methoxy-4'-pentylphenylcyclohexane ester, 4-ethoxy-4'-butylphenylcyclohexane ester, and 4-ethoxy-4'-propylphenylcyclohexane ester.

[0030] Examples of alkoxycyanobiphenyls include 4-cyano-4'-alkoxybiphenyls such as 4-cyano-4'-pentoxybiphenyl, 4-cyano-4'-butoxybiphenyl, and 4-cyano-4'-ethoxybiphenyl.

[0031] The solvent is typically in a liquid state at 298 K (24.85°C). The solvent may be in a solid state at 298 K (24.85°C). Any material with a melting point that becomes liquid at such a temperature during the upconversion film or upconversion body production process, or a material whose melting point can be lowered by mixing with an organic solvent, can be used. The solvent is typically capable of dissolving the sensitizing component and the luminescent component. The viscosity of the solvent at 23°C is, for example, 0.6 mPa·s or higher, preferably 4.0 mPa or higher. The viscosity of the solvent can be measured as the solution viscosity (mPa·s) of the coating liquid at a shear rate of 800 rpm under conditions of 23°C using any appropriate viscosity / viscoelasticity measuring device (e.g., a rheometer, product name "RS-600," manufactured by HAAKE). The boiling point of the solvent is, for example, 60°C or higher, preferably 80°C or higher, more preferably 150°C or higher, and even more preferably 200°C or higher. The upper limit of the boiling point of the solvent is typically 300°C, and typically 400°C. When a mixture of multiple solvents is used as the medium, the boiling point of the mixed solvent is defined as the temperature at which the weight loss rate is 95% when the mixed solvent is heated from 30°C to 400°C at 10°C / min by TG / DTA. When the viscosity and / or boiling point of the solvent contained in the color-forming portion are within these ranges, the solvent is less likely to volatilize during the production process and energy loss due to non-radiative deactivation can be suppressed, thereby further improving the absolute quantum yield of the upconversion film.

[0032] Examples of the solvent include organic solvents, and more specific examples include phthalate esters, glycerin, triglyceride compounds, and ionic liquids. The solvents may be used alone or in combination. Among the solvents, preferred are phthalate esters and triglyceride compounds.

[0033] Examples of phthalate esters include dimethyl phthalate, dibutyl phthalate, and dioctyl phthalate.

[0034] Examples of triglyceride compounds include tricaprin (1,2,3-tridecanoylglycerol), triacetin (glycerol triacetate), tricaprylin (glycerol tri-n-octanoate), and tricaproin (glycerol trihexanoate).

[0035] Among such media, room temperature liquid crystal compounds are preferred. When the medium contains a room temperature liquid crystal compound, the luminous efficiency of the upconversion film can be further improved.

[0036] The medium may contain an additive. Examples of additives include fatty acid oils such as MCT oil; and saturated hydrocarbons such as hexadecane and liquid paraffin. Additives differ from solvents in that they are defined as materials that do not have high dye solubility. "Not having high dye solubility" means that when a dye is added to and mixed with an additive at room temperature and normal pressure (23°C, 0.1 MPa), the dye solubility concentration is, for example, 0.1 mM or less. By including an additive in the medium, the viscosity, refractive index, and phase transition temperature of the medium can be suitably adjusted.

[0037] E. Matrix Examples of matrix materials include resin and glass. In one embodiment, the matrix is ​​made of resin. The resin is typically a water-soluble resin.

[0038] Any suitable water-soluble resin can be used as the water-soluble resin as long as it can form a matrix. Specific examples of water-soluble resins include polystyrene sulfonate, polyethylene oxide, polyethyleneimine, polyvinyl alcohol-based resins, and cellulose-based resins. Examples of polystyrene sulfonate include sodium polystyrene sulfonate. Examples of polyethyleneimine include polyethyleneimine hydrochloride. Examples of polyvinyl alcohol-based resins include polyvinyl alcohol, amine-modified polyvinyl alcohol, and carboxylic acid-modified polyvinyl alcohol. Examples of cellulose-based resins include hydroxyethyl cellulose. Among these water-soluble resins, polyethylene oxide and polyvinyl alcohol-based resins are preferred, and polyvinyl alcohol-based resins are more preferred. When the resin constituting the matrix contains polyethylene oxide and / or polyvinyl alcohol-based resin, the luminous efficiency of the upconversion film can be stably improved.

[0039] The Hansen solubility parameter (HSP) distance Ra between the resin constituting the matrix and the sensitizing component and the luminescent component is, for example, 10 (MPa) １／２ or more, for example, 11 (MPa) １／２ or more, preferably 12 (MPa) １／２ More preferably, 15 (MPa) １／２ More preferably, 18 (MPa) １／２ On the other hand, the HSP distance Ra between the resin constituting the matrix and the sensitizing component and the light-emitting component is, for example, 25 (MPa) １／２ and preferably 23 (MPa) １／２ More preferably, 21 (MPa) １／２ The HSP distance Ra in this range means that the affinity between the resin constituting the matrix and the sensitizing component and the luminescent component is low. As a result, the migration of the sensitizing component and the luminescent component into the matrix is ​​significantly suppressed, and the sensitizing component and the luminescent component can be stably present in the color-developing portion.

[0040] HSP is expressed as a vector obtained by dividing the Hildebrand solubility parameter into three components: dispersion force (δD), permanent dipole intermolecular force (δP), and hydrogen bonding force (δH), and plotting these components in three-dimensional space. Similar vectors can be determined to have high solubility. In other words, the similarity of solubility can be determined from the HSP distance Ra. The definition and calculation of HSP are described in "Hansen Solubility Parameters: A User's Handbook" by Charles M. Hansen (CRC Press, 2007). Known HSP values ​​are available for various resins and solvents, and these values ​​may be used directly, or values ​​calculated using the computer software HSPiP (Hansen Solubility Parameters in Practice) may be used. HSPiP also includes a database of resins and solvents.

[0041] Resin (HSP value: δD Ｒ , δP Ｒ , δH Ｒ ) and a sensitizing component or a luminescent component (HSP value: δD Ｃ , δP Ｃ , δH Ｃ The HSP distance Ra between the target and the target can be calculated by the formula (1): Ra = {4 × (δD Ｒ -δD Ｃ ) ２ + (δP Ｒ -δP Ｃ ) ２ + (δH Ｒ -δH Ｃ ) ２} １／２ ...(1) In formula (1), δD Ｒ is the dispersion force of the resin, δP Ｒ is the permanent dipole intermolecular force of the resin, δH Ｒ is the hydrogen bonding strength of the resin, δD Ｃ is the dispersion power of the sensitizing component or luminescent component, δP Ｃ is the permanent dipole intermolecular force of the sensitizing component or luminescent component, δH Ｃ represents the hydrogen bonding strength of the sensitizing component or the luminescent component, respectively.

[0042] F. Sensitizing Component and Light-Emitting Component F-1. Sensitizing Component As is clear from the mechanism described in Section A, the sensitizing component absorbs light (incident light), transitions from an excited singlet state to an excited triplet state through intersystem crossing, and induces triplet-triplet energy transfer in the light-emitting component. Examples of sensitizing components include compounds having a porphyrin structure, a phthalocyanine structure, or a fullerene structure. Such compounds may contain metal atoms in the molecule. Examples of metal atoms include Pt, Pd, Zn, Ru, Re, Ir, Os, Cu, Ni, Co, Cd, Au, Ag, Sn, Sb, Pb, P, and As. Pt, Pd, and Os are preferred. Specific examples of compounds that can function as sensitizing components will be described later in Section F-3.

[0043] The sensitizing component may be a quantum dot. The quantum dot may be made of any suitable material. The quantum dot may be made of preferably an inorganic material, more preferably an inorganic conductive material or an inorganic semiconducting material. Semiconductor materials include, for example, semiconductors of Groups II-VI, III-V, IV-VI, and IV. Specific examples include Si, Ge, Sn, Se, Te, B, C (including diamond), P, BN, BP, BAs, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, InN, InP, InAs, InSb, AlN, AlP, AlAs, AlSb, GaN, GaP, GaAs, GaSb, Z nO, ZnS, ZnSe, ZnTe, CdS, CdSe, CdSeZn, CdTe, HgS, HgSe, HgTe, BeS, BeSe, BeTe, MgS, MgSe, GeS, GeSe, GeTe, SnS, SnSe, SnTe, PbO, PbS, PbSe, PbTe, CuF, CuCl, CuBr, CuI, Si ３ N ４ , Ge ３ N ４ , Al ２ O ３ , (Al, Ga, In) ２ (S, Se, Te) ３ , Al ２ CO, and combinations (complexes) thereof.

[0044] The sensitizing component is preferably 7.00×10 －９ mol~5.00×10 －６ mol, more preferably 1.00 x 10 －８ mol~3.00×10 －６ mol, more preferably 4.50 × 10 －８ mol~2.00×10 －６ When the content of the sensitizing component is within this range, triplet excitons can be generated sufficiently, and the efficiency of triplet-triplet annihilation can be improved.

[0045] F-2. Light-Emitting Component As is clear from the mechanism described in Section A, the light-emitting component receives triplet-triplet energy transfer from the sensitizing component to generate an excited triplet state, and the light-emitting component molecules in the excited triplet state approach each other at a distance that allows diffusion, collision, or energy transfer, causing triplet-triplet annihilation to generate an excited singlet of a higher energy level. Various compounds having fused aromatic rings are known as light-emitting components. Specific examples include compounds having a naphthalene structure, an anthracene structure, a pyrene structure, a perylene structure, a tetracene structure, a bodipyrromethene structure, and a diketopyrrolopyrrole structure. Specific examples of compounds that can function as light-emitting components will be described later in Section F-3.

[0046] The amount of the luminescent component is preferably 5.00×10 －６ mol~7.00×10 －５ mol, more preferably 6.00 x 10 －６ mol~6.00×10 －５ mol, more preferably 7.00 × 10 －６ mol~5.00×10 －５ When the content of the luminescent component is in this range, triplet excitons received from the sensitizing dye can diffuse sufficiently between the luminescent component molecules.

[0047] The blending ratio of the sensitizing component to the luminescent component (sensitizing component:luminescent component) (molar ratio) is, for example, 1:10 to 1:7000, preferably 1:25 to 1:3000, more preferably 1:30 to 1:200, and even more preferably 1:35 to 1:100. When the blending ratio is within this range, triplet excitons generated from the sensitizing component are efficiently transferred to the luminescent dye, deactivation between the luminescent dyes is minimized, and triplet-triplet annihilation can be satisfactorily achieved.

[0048] F-3. Combination of Sensitizing Component and Light-Emitting Component Preferred combinations of sensitizing components and light-emitting components according to the wavelengths of incident light and upconversion light are as follows:

[0049] The sensitizing component that absorbs light in the wavelength region λ1 of 510 nm to 550 nm is the following compound, and the light-emitting component that emits (emits) light in the wavelength region λ2 of 400 nm to 500 nm is the following compound. This combination can upconvert green light to blue light. <Sensitizing Component> <Luminescent components>

[0050] The sensitizing component that absorbs light in the wavelength region λ1 of 610 nm to 650 nm is the following compound, and the light-emitting component that emits (emits) light in the wavelength region λ2 of 500 nm to 600 nm is the following compound. This combination can upconvert red light to yellow-green light. <Sensitizing Component> <Luminescent components>

[0051] The sensitizing component that absorbs light in the wavelength region λ1 of 700 nm to 810 nm is the following compound, and the light-emitting component that emits (emits) light in the wavelength region λ2 of 500 nm to 700 nm is the following compound. This combination can upconvert near-infrared light to visible light (red light to green light). <Sensitizing Component> <Luminescent components>

[0052] The sensitizing component that absorbs light in the wavelength region λ1 of 700 nm to 730 nm is the following compound, and the light-emitting component that emits (emits) light in the wavelength region λ2 of 400 nm to 500 nm is the following compound. This combination can upconvert near-infrared light to visible light (blue light). <Sensitizing Component> <Luminescent components>

[0053] The sensitizing component that absorbs light in the wavelength region λ1 of 410 nm to 500 nm is the following compound, and the light-emitting component that emits (emits) light in the wavelength region λ2 of 300 nm to 400 nm is the following compound. This combination can upconvert blue light to ultraviolet light. <Sensitizing Component> <Luminescent components>

[0054] The sensitizing component that absorbs light in the wavelength region λ1 of around 630 nm to 640 nm (e.g., 635 nm) is quantum dots (CdSe, CdSe / ZnS), and the light-emitting component that emits (emits) light in the wavelength region λ2 of around 440 nm to 460 nm (e.g., 450 nm) is the following compound. This combination can upconvert near-infrared light to visible light (blue light). <Light-emitting component>

[0055] The sensitizing component that absorbs light in the wavelength region λ1 of around 970 nm to 990 nm (for example, 980 nm) is quantum dots (PbSe, PbS / CdS), and the light-emitting component that emits (emits) light in the wavelength region λ2 of around 550 nm to 570 nm (for example, 560 nm) is the following compound. This combination can upconvert near-infrared light to visible light (green light). <Light-emitting component>

[0056] G. Surfactant The photon upconversion film may further contain a surfactant. When the photon upconversion film contains a surfactant, the dispersibility of the color-producing moiety in the matrix can be improved. Examples of surfactants include cationic surfactants such as hexadecyltrimethylammonium bromide (CTAB), anionic surfactants, and nonionic surfactants, and CTAB is preferred. The surfactant is added in an amount of, for example, 0 to 200 parts by weight, preferably 1 to 50 parts by weight, per 100 parts by weight of the medium.

[0057] H. Method for Producing a Photon Up-Conversion Film In one embodiment, a method for producing a photon up-conversion film includes preparing an emulsion from an aqueous solution containing a water-soluble resin and a solution or dispersion of a sensitizing component and a light-emitting component (hereinafter, collectively referred to as a "dye solution, etc."); applying the emulsion to a substrate to form a coating film; and drying the coating film. Each step will be described in detail below.

[0058] <Preparation of Emulsion> In preparing the emulsion, first, a dye solution and the like appropriate for the desired upconversion film are prepared.

[0059] When producing an upconversion film (UC film) using a medium that is fluid at 298 K (24.85°C), an organic solvent is added to the medium described in Section C above (specifically, the room-temperature liquid crystal compound and / or solvent), if necessary, followed by the addition and stirring of the sensitizing component and the light-emitting component described in Section F above. Adding an organic solvent to the medium can improve the solubility of the sensitizing component and the light-emitting component. In particular, when the fluid medium is a room-temperature liquid crystal compound, adding an organic solvent to the room-temperature liquid crystal compound is preferable. Examples of organic solvents that can be used include volatile solvents. Specific examples of such solvents include ethers such as tetrahydrofuran; halogenated hydrocarbons such as chloroform and dichloromethane; and toluene. Organic solvents can be used alone or in combination. Among these organic solvents, ethers are preferred, and tetrahydrofuran is more preferred. The organic solvent is added in an amount of, for example, 0 to 200 parts by weight, preferably 80 to 120 parts by weight, per 100 parts by weight of the fluid medium. The medium may also contain the additives described above. The additive may be added to the medium together with the organic solvent, or the additive may be added alone. Adding an additive to the medium can appropriately adjust the viscosity, refractive index, and / or phase transition temperature of the medium. The additive is added in an amount of, for example, 0 to 200 parts by mass, preferably 5 to 100 parts by mass, per 100 parts by mass of the medium. Furthermore, multiple types of liquid crystal compounds, organic solvents, and other additives may be mixed in any desired mixing ratio.

[0060] Furthermore, when an upconversion film (UC film containing a high-temperature liquid crystal compound) is produced using a high-temperature liquid crystal compound, the high-temperature liquid crystal compound described in the above section C is heated to a liquid crystal state, and then the above-mentioned organic solvent is added as needed, and the sensitizing component and the light-emitting component described in the above section F are added and stirred. The heating temperature of the high-temperature liquid crystal compound can be arbitrarily and appropriately adjusted depending on the high-temperature liquid crystal compound. The heating temperature of the high-temperature liquid crystal compound can be adjusted, for example, to a temperature higher than the crystalline-liquid crystal phase transition temperature T Ｋ－Ｎ or more, and the phase transition temperature T Ｎ－ＩThe following is true. Adding an organic solvent to a high-temperature liquid crystal compound in a liquid crystal state can improve the solubility of the sensitizing component and the light-emitting component. The proportion of the organic solvent added is, for example, 0 to 200 parts by mass, and preferably 80 to 120 parts by mass, per 100 parts by mass of the high-temperature liquid crystal compound. This allows the preparation of a dye solution or the like suitable for producing a UC film with a relaxation time of less than 210 ms. The dye solution or the like is typically a medium in which the sensitizing component and the light-emitting component are dissolved and / or dispersed.

[0061] The concentration of the sensitizing component in these dye solutions or the like may be, for example, 0.001 mM to 1 mM, and the concentration of the luminescent component may be, for example, 1 mM to 50 mM.

[0062] Also, prepare an aqueous solution of the water-soluble resin described above in Section E. The concentration of the aqueous solution may be, for example, 3% to 20% by weight, or, for example, 5% to 10% by weight.

[0063] Next, an aqueous solution of the water-soluble resin is mixed with a dye solution, etc., so that the blending ratio of the sensitizing component and the luminescent component relative to the water-soluble resin (matrix) falls within the desired range described in Section F above. More specifically, the aqueous solution of the water-soluble resin is mixed with the dye solution, etc., and the mixture is emulsified using a homogenizer. At this time, the surfactant described above may be added, if necessary. This allows droplets of the dye solution, etc., to be suitably dispersed in the aqueous solution of the water-soluble resin, thereby preparing an emulsion. If necessary, the resulting emulsion may be degassed. Furthermore, volatile components (e.g., organic solvents) contained in the resulting emulsion may be distilled off under reduced pressure. This allows the concentrations of the sensitizing component and the luminescent component in the emulsion to be improved. The volume fraction of the emulsion particles is, for example, 5% to 60%. The average particle diameter of the emulsion particles is, for example, 0.1 μm to 10 μm. When the volume fraction and / or average particle diameter of the emulsion particles are within these ranges, a color-developing portion having a desired size can be formed as a dispersed phase in the upconversion film.

[0064] <Formation and Drying of Coating Film> Next, the emulsion obtained above is applied to a substrate to form a coating film. Typical examples of the substrate include a resin sheet or glass. Any appropriate resin can be used as the resin constituting the resin sheet. Specific examples include polyimide-based resins, cellulose-based resins such as triacetyl cellulose (TAC), polyester-based resins such as polyethylene terephthalate (PET), polyvinyl alcohol-based resins, polycarbonate-based resins, polyamide-based resins, polyethersulfone-based resins, polysulfone-based resins, polystyrene-based resins, polynorbornene-based resins, polyolefin-based resins, (meth)acrylic-based resins, acetate-based resins, and other transparent resins. Other examples include thermosetting resins or ultraviolet-curing resins such as (meth)acrylic-based resins, urethane-based resins, (meth)acrylic urethane-based resins, epoxy-based resins, and silicone-based resins. Other examples include glassy polymers such as siloxane-based polymers.

[0065] Any appropriate coating method can be used. Specific examples include roll coating, spin coating, wire bar coating, dip coating, die coating, curtain coating, spray coating, and knife coating (such as comma coating). A coating film can also be formed using a drum coating machine. In this case, the coating roll (drying roll) of the drum coating machine can function as the substrate. The coating roll (drying roll) is made of a metal such as nickel, chromium, copper, iron, or stainless steel. The temperature of the emulsion during coating can be, for example, 10°C to 60°C. The thickness of the coating film is adjusted so that the thickness of the resulting upconversion film falls within the desired range described in Section B above (e.g., 5 μm to 200 μm). The thickness of the coating film can be, for example, 100 μm to 1000 μm.

[0066] The coating is then dried. Drying is carried out by any suitable means (for example, an oven). The drying temperature can be, for example, 60°C to 90°C, and the drying time can be, for example, 20 to 60 minutes. By drying, a dried coating having substantially the same thickness as the resulting upconversion film can be obtained. The dried coating can typically be allowed to cool naturally to room temperature (23°C). In this way, an upconversion film is prepared. The upconversion film may be peeled off from the substrate, or it can be used as a laminate with the substrate without being peeled off from the substrate.

[0067] I. Uses of Photon Upconversion Films The upconversion films described in Sections A to H above can be applied to any suitable industrial product. Examples of industrial products include laminates and energy conversion devices. Therefore, one embodiment of the present invention also encompasses laminates and energy conversion devices using such upconversion films. A laminate includes an upconversion film described in Sections A to H above and any suitable film (layer) laminated on the upconversion film. An energy conversion device includes at least an upconversion film described in Sections A to H above, and may further include any suitable configuration in addition to the upconversion film.

[0068] I-1. Laminate The laminate may include a first protective layer and a second protective layer disposed on the light-incident surface and the light-exiting surface of the upconversion film, respectively. The first protective layer and the second protective layer may be omitted depending on the purpose. Furthermore, as long as the effects of the present invention are achieved, any appropriate optical member may be disposed between the upconversion film and the first protective layer and / or between the upconversion film and the second protective layer. In one embodiment, the laminate has a configuration in which at least the first protective layer to the second protective layer are integrated. Here, "the first protective layer to the second protective layer are integrated" means that each of the components constituting the laminate, from the first protective layer to the second protective layer, is connected as a whole. Integration can be achieved, for example, by bonding adjacent components together via an adhesive layer such as a pressure-sensitive adhesive layer or an adhesive layer. Furthermore, a layer with a different function, such as an overcoat, may be directly applied to the photon upconversion film. Preferably, the first protective layer, the upconversion film, the second protective layer, and any optional protective layers are integrated via an adhesive layer. The overcoat is made of any appropriate material. Examples of overcoat materials include acrylic resins and epoxy resins. In another embodiment, the laminate has a configuration in which the first protective layer and the second protective layer are not integrated. Here, "the first protective layer and the second protective layer are not integrated" means that at least one of the components from the first protective layer to the second protective layer constituting the laminate is simply laminated on one or both of the adjacent components. The laminate in this embodiment may have a configuration in which the first protective layer, the upconversion film, and the second protective layer are arranged in this order without an adhesive layer. Furthermore, for example, the laminate in this embodiment may have a configuration in which the components from the first protective layer to the upconversion film are integrated via an adhesive layer, and the second protective layer is arranged on the light-emitting side of the integrated laminate without an adhesive layer.Furthermore, for example, the laminate in this embodiment may have a configuration in which the upconversion film to the second protective layer are integrated via an adhesive layer, and the first protective layer is positioned on the light incident side of the integrated laminate without an adhesive layer in between.

[0069] I-2. Protective Layer The first and second protective layers are each formed of any suitable film that can be used as a protective layer for an upconversion film. Specific examples of materials that can serve as the main component of the film include cellulose-based resins such as triacetyl cellulose (TAC), and transparent resins such as polyesters, polyvinyl alcohols, polycarbonates, polyamides, polyimides, polyethersulfones, polysulfones, polystyrenes, polynorbornenes, polyolefins, (meth)acrylics, and acetates. Other examples include thermosetting or ultraviolet-curing resins such as (meth)acrylics, urethanes, (meth)acrylic urethanes, epoxy resins, and silicones, as well as inorganic materials such as glass and silica. Other examples include glassy polymers such as siloxane-based polymers. Polymer films described in JP 2001-343529 A (WO 01 / 37007) can also be used. Examples of materials that can be used for this film include a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in its side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in its side chain, such as a resin composition containing an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile-styrene copolymer. The polymer film can be, for example, an extrusion molded product of the above resin composition.

[0070] J. Photon Upconversion Materials Sections A to H above provide a detailed description of upconversion films. However, as long as upconversion is possible in a solid state, there is no limitation to the film shape. Photon upconversion materials are in a solid state at room temperature (23°C) and normal pressure (0.1 MPa). Examples of the shape of photon upconversion materials include crystals, powders, and gels. Photon upconversion materials can be described in the same way as upconversion films, except for their solution state. Therefore, a description of photon upconversion materials will be omitted.

[0071] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" and "%" in the examples are by weight.

[0072] Example 1 1. Preparation of a DMP solution of a sensitizing component and a luminescent component Octaethylporphyrin platinum (PtOEP: chemical formula below) as a sensitizing component and 9,10-diphenylanthracene (DPA: chemical formula below) as a luminescent component were dissolved in dimethyl phthalate (DMP) in a glove box to prepare a DMP solution of the sensitizing component and the luminescent component. The concentration of the sensitizing component in the solution was 2.39 × 10 ―７ M, and the concentration of the luminescent component is 4.78 × 10 ―５ That is, the molar ratio of the sensitizing component to the light-emitting component was 1:200. The prepared solution was stored in a sealed vial until the emulsification step. <Sensitizing component> <Luminescent components>

[0073] 2. Preparation of Emulsion: 0.4 ml of the solution obtained above was added to 5 g of a 9% by mass aqueous solution of polyvinyl alcohol (PVA). The solution was injected using a 0.75 mm inner diameter tube and stirred (17,500 rpm) with a homogenizer until the entire mixture was emulsified. Argon gas was sprayed onto the resulting emulsion for approximately 2 minutes, and the mixture was stirred using a mixer (THINKY) in mixing mode (2,000 rpm) for 5 minutes and in degassing mode (2,200 rpm) for 5 minutes. In this way, an emulsion was prepared. The PVA used had a degree of polymerization of 1,700 and a degree of saponification of 99%.

[0074] 3. Formation of Upconversion Film The emulsion obtained above was applied to a polyimide film (substrate) using an applicator to a coating thickness of 700 μm. The coating / polyimide film laminate was dried in a thermostatic chamber. The drying temperature was 80°C, and the drying time was 30 minutes. After drying, the laminate was allowed to cool naturally to room temperature (23°C). Finally, the dried coating film was peeled off from the polyimide film to obtain an upconversion film (thickness 63 μm). Note that the steps after emulsion preparation were carried out in air in a dark place (under an environment with only darkroom light).

[0075] Example 2 An upconversion film was obtained in the same manner as in Example 1, except that the DMP solution of the sensitizing component and the light-emitting component was changed to a crystal solution of the sensitizing component and the light-emitting component prepared as follows. At room temperature (23°C), 100 parts by mass of 5CB (4-cyano-4'-pentylbiphenyl) was added to 100 parts by mass of tetrahydrofuran (THF) and stirred to prepare a liquid crystal solvent. Next, PtOEP as the sensitizing component and DPA as the light-emitting component were dissolved in the liquid crystal solvent to prepare a liquid crystal solution of the sensitizing component and the light-emitting component.

[0076] Example 3 An up-conversion film was obtained in the same manner as in Example 2, except that 5CB was changed to 7CB (4-cyano-4'-heptylbiphenyl).

[0077] Example 4 An upconversion film was obtained in the same manner as in Example 1, except that the DMP solution of the sensitizing component and the light-emitting component was changed to a crystalline solution of the sensitizing component and the light-emitting component prepared as follows. 100 parts by mass of 5OCB (4-cyano-4'-pentyloxybiphenyl) was heated to 60°C in a water bath to produce a liquid crystal state, and 100 parts by mass of tetrahydrofuran was added and mixed with stirring to prepare a liquid crystal solvent. Next, PtOEP as the sensitizing component and DPA as the light-emitting component were dissolved in the liquid crystal solvent to prepare a liquid crystal solution of the sensitizing component and the light-emitting component.

[0078] Example 5 An up-conversion film was obtained in the same manner as in Example 2, except that the PVA aqueous solution was changed to a polyethylene oxide (PEO) aqueous solution (molecular weight 200,000) (9% by mass).

[0079] Example 6 An upconversion film was obtained in the same manner as in Example 2, except that the sensitizing component was changed to meso-tetraphenyl-tetraanthraporphyrin palladium (PdTPTAP: chemical formula below) and the luminescent component was changed to rubrene (chemical formula below). The PdTPTAP concentration in the solution was 0.554 mM, and the rubrene concentration was 20 mM. That is, the molar ratio of sensitizing component to luminescent component was 1:36. Sensitizing Component <Luminescent components>

[0080] Example 7 At room temperature (23°C), 100 parts by mass of 5CB (4-cyano-4'-pentylbiphenyl) was added with PtOEP as a sensitizing component, DPA as a light-emitting component, 100 parts by mass of tetrahydrofuran (THF), and 5 parts by mass of MCT oil, and the mixture was stirred and mixed to prepare a liquid crystal solvent. The liquid crystal solution was added to 1 mL of a 1% by mass aqueous solution of CTAB (surfactant solution), and the mixture was stirred with an ultrasonic homogenizer to prepare an emulsion solution. 1.8 mL of the solution obtained above was added to 5 g of an aqueous solution of polyvinyl alcohol (PVA) (9% by mass). The subsequent procedures were the same as in Example 1, and an upconversion film was obtained.

[0081] Example 8 An up-conversion film was obtained in the same manner as in Example 7, except that 5CB was changed to PCH5CN (4-cyano-4'-pentylphenylcyclohexane).

[0082] Example 9 An up-conversion film was obtained in the same manner as in Example 7, except that 5CB was changed to 5OCB (4-cyano-4'-pentyloxybiphenyl).

[0083] Example 10 An upconversion film was obtained in the same manner as in Example 7, except that 5 parts by mass of MCT oil was changed to 5 parts by mass of hexadecane.

[0084] Example 11 An upconversion film was obtained in the same manner as in Example 7, except that 5 parts by mass of MCT oil was changed to 5 parts by mass of liquid paraffin.

[0085] Example 12 An upconversion film was obtained in the same manner as in Example 7, except that the sensitizing component was changed to meso-tetraphenyl-tetraanthraporphyrin palladium (PdTPTAP: chemical formula shown above) and the luminescent component was changed to rubrene (chemical formula shown above). The concentrations were the same as in Example 6.

[0086] Example 13 An up-conversion film was obtained in the same manner as in Example 2, except that 5CB was changed to ZLI1052 (a mixed liquid crystal of PE105 (4-pentylphenyl 4-methoxybenzoate) and PE605 (4-pentylphenyl 4-hexyloxybenzoate)).

[0087] Example 14 An upconversion film was obtained in the same manner as in Example 2, except that 5CB was changed to ZLI1132 (a mixed liquid crystal of PCH-3CN (4-cyano-4'-propylphenylcyclohexane), PCH-5CN (4-cyano-4'-pentylphenylcyclohexane), PCH-7CN (4-cyano-4'-phenylcyclohexane), and BCH-5CN (4-cyano-4'-pentylbiphenylcyclohexane)).

[0088] Example 15 An upconversion film was obtained in the same manner as in Example 2, except that 5CB was changed to ZLI1083 (a mixed liquid crystal of PCH-3CN (4-cyano-4'-propylphenylcyclohexane), PCH-5CN (4-cyano-4'-pentylphenylcyclohexane), and PCH-7CN (4-cyano-4'-phenylcyclohexane)).

[0089] Example 16 An upconversion film was obtained in the same manner as in Example 2, except that 5CB was changed to E7 (a mixed liquid crystal of 5CB (4-cyano-4'-pentylbiphenyl), 7CB (4-cyano-4'-heptylbiphenyl), 8OCB (4-cyano-4'-n-octyloxybiphenyl), and 5CT (4-cyano-4'-pentyl-p-terphenyl)).

[0090] Example 17 An upconversion film was obtained in the same manner as in Example 2, except that 5CB was changed to E8 (a mixed liquid crystal of 5CB (4-cyano-4'-pentylbiphenyl), 7CB (4-cyano-4'-heptylbiphenyl), 5OCB (4-cyano-4'-pentyloxybiphenyl), 8OCB (4-cyano-4'-n-octyloxybiphenyl), and 5CT (4-cyano-4'-pentyl-p-terphenyl)).

[0091] Example 18 An up-conversion film was obtained in the same manner as in Example 1, except that DMP was changed to tricaprin.

[0092] Example 19 A liquid crystal solvent was prepared in the same manner as in Example 4. In addition, glass was placed on a hot plate heated to 80°C, and the liquid crystal solvent was placed on the glass to volatilize the THF. This resulted in a crystalline upconversion product.

[0093] Comparative Example 1: An upconversion film (thickness: 60 μm) was obtained in the same manner as in Example 1, except that toluene was used instead of DMP. Comparative Example 2: An upconversion film was obtained in the same manner as in Example 6, except that toluene was used as the crystallization solvent.

[0094] <Relaxation Time Measurement by Time-Domain Nuclear Magnetic Resonance (TD-NMR)> The upconversion film or upconversion body obtained in the above examples was cut into strips to prepare samples. The short side of each sample measured 1.5 cm, and the long side measured 7 to 12 cm. Approximately two to four samples were inserted into a sample tube. The samples in the sample tube were then measured at 298 K using the spin-echo method with TD-NMR (pulse NMR). The free induction decay curve of the spin-spin relaxation of the obtained 1H nuclei was analyzed using the nonlinear least-squares method to calculate the T2 relaxation time. The results are shown in Tables 1 to 3. The measurement conditions were a repetition time of 10 s, 8 integrations, and 50 measurement points. Measurements were performed in a range where the relative signal intensity of the final plot, when the signal intensity of the first plot was normalized by 1, was between 0.1 and 0.001, and the relaxation time was analyzed. The analytical software "TDNMR-A Version 6.9 Rev 2.0" manufactured by BRUKER was used, and fitting was performed using an exponential type with a Weibull coefficient of 1 according to the product manual. When a Weibull coefficient of 1 was not appropriate for some samples, an optimal value in the range of 1 to 2 was used. The measurement conditions are described below. Apparatus: TD-NMR (the minispec mq20) manufactured by Bruker. Detected nuclides: １ H Measurement temperature: 298K Measurement technique: Spin-echo method Analysis method: Nonlinear least squares method Scan: 8 Recycle delay: 10 sec First 90-180 Pulse Separation: 0.0082 Final 90-180 Pulse Separation: Adjusted to the conditions described above Number of Data Points for Fitting: 50 When two or more components were detected in the obtained relaxation time, the obtained relaxation time was multiplied by the proton ratio, and an average value was calculated from the relaxation times obtained as the sum of all the components, and this average value was used as the relaxation time.

[0095] <Absolute Quantum Yield Measurement> The upconversion luminescence absolute quantum yield (100% equivalent) of the upconversion films or upconversion bodies (hereinafter referred to as samples) obtained in the above Examples and Comparative Examples was measured using an absolute quantum yield measurement system Quantaurus-QY Plus C11347-02 (manufactured by Hamamatsu Photonics, detection wavelength: 400 to 1100 nm). For the absolute quantum yield measurement, a diode laser (808 nm, 200 mW, 532 nm, 75 mW, 460 nm, 500 mW, RGB Photonics) was used as an excitation source, and the light intensity was adjusted using the laser output and an ND filter. 808 nm was 27,000 mW / cm ２ , 532 nm is 31,000 mW / cm ２ , 460 nm is 31000 mW / cm ２ The measurement was performed by adjusting the light intensity so that the sample was irradiated with light at 1000 kJ / cm. The measured absolute quantum yields are shown in Tables 1 to 3.

[0096] <Transmittance Measurement> The transmittance of the upconversion films or upconversion bodies obtained in the above Examples and Comparative Examples was measured using a UV-Vis-Near-Infrared Spectrometer UH4150 (manufactured by Hitachi High-Technologies Corporation). For transmittance measurement, the sample was placed directly in front of an integrating sphere, and total light transmittance was measured in the wavelength range of 400 nm to 800 nm at 1 nm intervals. In this case, the average value of the obtained transmittances from 400 nm to 800 nm was used as the average transmittance. The measured average transmittances are shown in Tables 1 to 3.

[0097]

[0098]

[0099]

[0100] [Evaluation] As is clear from Tables 1 to 3, when the T2 relaxation time measured by the TD-NMR spin-echo method at 298 K is less than 210 ms, it is possible to improve the absolute quantum yield and the upconversion luminescence efficiency.

[0101] The photon upconversion films and photon upconversion bodies according to the embodiments of the present invention can be suitably used in solar cells or photovoltaic power generation, photocatalysis, bioimaging, optical instruments, laminates, energy conversion devices, and the like.

Claims

1. A color-developing portion including at least a sensitizing component capable of absorbing light in a first wavelength region λ1 and a light-emitting component capable of emitting light in a second wavelength region λ2 having a shorter wavelength than the first wavelength region λ1; The color-developing portion contains a solvent having a boiling point of 80° C. or higher, A photon up-conversion film having a relaxation time of less than 210 ms as measured by the spin-echo method using time-domain nuclear magnetic resonance (pulsed NMR) at 298K.

2. A photon upconversion film as described in claim 1, wherein the color-developing portion contains a solvent having a viscosity of 0.6 mPa·s or more at 23°C.

3. A color-developing element comprising at least a sensitizing component capable of absorbing light in a first wavelength region λ1 and a light-emitting component capable of emitting light in a second wavelength region λ2 having a shorter wavelength than the first wavelength region λ1; The color-developing portion contains a solvent having a viscosity of 0.6 mPa·s or more at 23° C., A photon up-conversion film having a relaxation time of less than 210 ms as measured by the spin-echo method using time-domain nuclear magnetic resonance (pulsed NMR) at 298K.

4. Equipped with a matrix, The photon upconversion film according to claim 1 , wherein the color-developing portion is dispersed in the matrix as a dispersed phase.

5. The photon upconversion film according to claim 4 , wherein the matrix is ​​made of a resin.

6. The photon upconversion film of claim 5 , wherein the resin comprises a polyethylene oxide and / or a polyvinyl alcohol-based resin.

7. The photon up-conversion film according to claim 1 , wherein the color-developing portion contains a monomolecular liquid crystal compound.

8. The sensitizing component was added at 7.00×10 －９ mol~5.00×10 －６ mol and the luminescent component is 5.00×10 －６ mol~7.00×10 －５ The photon upconversion film of claim 5 , comprising:

9. A method for producing the photon up-conversion film according to any one of claims 1 to 3, comprising the steps of: preparing an emulsion from a medium in which the sensitizing component and the light-emitting component are dispersed and / or dissolved, and an aqueous solution containing a water-soluble resin; applying the emulsion to a substrate to form a coating film; and drying the coating film.

10. A laminate comprising the photon upconversion film according to claim 1 .

11. An energy conversion device comprising the photon upconversion film according to any one of claims 1 to 3.